linux-kernel - [PATCH] clockevents: Shutdown detached clockevent device

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Message-Id: <eef0a91c51b74d4e52c8e5a95eca27b5a0563f07.1428650683.git.viresh.kumar@linaro.org>
Date:	Fri, 10 Apr 2015 12:56:41 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH] clockevents: Shutdown detached clockevent device

A clockevent device is marked DETACHED when it is replaced by another
clockevent device.

The device is shutdown properly for drivers that implement legacy
->set_mode() callback, as we call ->set_mode() for CLOCK_EVT_MODE_UNUSED
as well.

But for the new per-state callback interface, we skip shutting down the
device, as we thought its an internal state change. That wasn't correct.

The effect is that the device is left programmed in oneshot or periodic
mode.

Fall-back to 'case CLOCK_EVT_STATE_SHUTDOWN', to shutdown the device.

Fixes: bd624d75db21 ("clockevents: Introduce mode specific callbacks")
Reported-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---

Tested on Samsung's Arndale (Dual Cortex A15) board.

 kernel/time/clockevents.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 25d942d1da27..629be4e21e96 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -117,11 +117,7 @@ static int __clockevents_set_state(struct clock_event_device *dev,
 	/* Transition with new state-specific callbacks */
 	switch (state) {
 	case CLOCK_EVT_STATE_DETACHED:
-		/*
-		 * This is an internal state, which is guaranteed to go from
-		 * SHUTDOWN to DETACHED. No driver interaction required.
-		 */
-		return 0;
+		/* The clockevent device is getting replaced. Shut it down. */
 
 	case CLOCK_EVT_STATE_SHUTDOWN:
 		return dev->set_state_shutdown(dev);
-- 
2.3.0.rc0.44.ga94655d

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